Property

A property is any of several on-or-off traits of the hero or a monster. Properties include the resistances, the effects of rings, the temporary effects of certain potions, negative effects (as confusion, stoning), and others. A property may be intrinsic or extrinsic.

You might gain it as an innate property of your role or race. For some innate properties, you need to first reach a certain experience level. For example, a Barbarian starts with poison resistance and gains intrinsic speed at level 7.

The following tables provide a brief description of each property that the hero might have, and some notable sources of that property. (The property may have other sources.) The individual articles for each property might provide more details.

The left column also gives the associated constant from prop.h, if any. The right column may refer to a monster flag (like M1_FLY); then you may search monst.c to find a monster with that flag for polymorph.

It is possible to receive any of these properties as intrinsics that never time out. Some are also available as extrinsics, or as temporary intrinsics. This list includes each property that may be intrinsic, even if the only way is to eat the correct ring. (Eating a ring has a chance to fail to convey the property!)

You may receive any of these properties in this table as a temporary intrinsic, but not as a permanent intrinsic. After a specific number of turns, you lose the temporary intrinsic. That may be well, because most of these properties have bad effects; you would want them to wear off over time.

Movement commands may cause you to step in a random direction, and you may hit pets by mistake. Direction of Zapping, spellcasting and firing also has a high chance of being randomized. Prevents teleport control.

Gives a random appearance to any monster or object on the map, so that you do not know who or what you see. In SLASH'EM, hallucination also distorts the view of objects on the same square as you, including your inventory.

These temporary intrinsics do not only time out and go away, they also do something (typically to cause instadeath) when they time out. When you have one of these properties, you only have some number of turns to remove the property and avoid its time-out effect.

The adjective intrinsic refers to something that is internal, inherent, within the body. We also use the term as a noun. The antonym of intrinsic is extrinsic.

Oddly, sometimes we also use the term "intrinsic" to refer to any property, whether that property is intrinsic or extrinsic. For example, we might refer to an "intrinsic" from a ring, though the ring is external to the character. This leads to oxymoronic phrases such as "extrinsic intrinsic".

The usage of "intrinsic" to mean "extrinsic" occurs in other pages on this wiki, and even within the source code of NetHack. For example, the comment at the top of wield.c refers to wielded weapons conveying intrinsics, though they would actually convey extrinsics. The set_artifact_intrinsic function in artifact.c is another example of this usage. The mintrinsics field of struct monst stores information about both intrinsic and extrinsic resistances of the monsters.[4]

The struct prop that tracks properties has only separated "intrinsic" and "extrinsic" since NetHack 3.3.0.[5]

One can justify the use of "intrinsic" to mean "extrinsic". For example, an amulet versus poison may be extrinsic to your body, but when you wear it, the effect spreads inside your body and becomes intrinsic. When you eat that kobold shaman corpse, or land on poison in a spiked pit, then the poison enters your body but has no effect. There must be some intrinsic defense in your body that stops the poison, though the ring remains outside on your finger. This explanation would not work so well for an amulet of reflection.

If you quaff a potion that provides a property, it is an intrinsic or extrinsic property? One argument states that the contents of the potion enters your body, so the property must be intrinsic. (A look at struct prop supports that argument.) The other argument states any property from an item, including a potion, is an extrinsic. The potion of blindness seems to grant intrinsic blindness (not extrinsic blindness, which you could #wipe away), but the potion of speed seems to grant extrinsic speed, equivalent with speed boots.

If you acquire a property through polymorph, it is an intrinsic or extrinsic property? One argument notes that the property is intrinsic to your current form; the other argument provides that your current form is extrinsic to your true form.

The source code defines most of the properties at prop.h, line 8. Each property has a representative integer constant. Particularly in objects.c and artilist.h, the integer constants assign the properties granted by using certain items. The integer constants also serve as array indexes into the u.uprops, an array of struct prop that records the source of each of the hero's intrinsics and extrinsics.

While food appraisal and paralysis do not have constants in prop.h, they behave like other intrinsics, thus their inclusion in the lists on this page.